South Korea's spy chief said on Wednesday the kidnappers were changing locations frequently to evade Afghan and international forces. The hostages were believed to be split up and held at nine villages in three regions, according to a member of the South Korean parliament's intelligence committee.
The second slain hostage was identified as Shim Sung-min, 29, a former employee of an IT firm who did volunteer work to help the poor. He was shot after the expiry of other deadlines the Taliban had set for the release of rebel prisoners.
His body was dumped in a field beside a road in Arzoo, 80 km (50 miles) from where the group of 18 women and five men were seized on the main road south from Kabul on July 19.
Negotiations are deadlocked with Afghan authorities seeking the release of the 18 women before any prisoners are freed and the kidnappers insisting its fighters be freed first, a Western security analyst said.
South Korea has sent a special envoy to Kabul, who has held talks with Afghan officials including President Karzai.
"The government is well aware of how the international community deals with these kinds of abduction cases," President Roh Moo Hyun's spokesman said in a statement.
"But it also believes that it would be worthwhile to use flexibility in the cause of saving the precious lives of those still in captivity, and is appealing to the international community to do so."
The seizure of the Koreans came a day after the Taliban had seized two Germans and five Afghans in nearby Wardak province.
The body of one of the Germans was found with bullet wounds, but the other German and four Afghans were still being held by the insurgents, who want Germany to pull its troops out of Afghanistan. One Afghan captive managed to escape.
Al Jazeera showed a man against a rocky backdrop in a hilly area, a militant covering him with a rocket-propelled grenade.
The station did not play the sound of the video, but a presenter said: "The German hostage Rudolf B. ... urged Germany and the United States to pull out their forces from Afghanistan and urged his country to help save his life and secure his return to his homeland and family."
German Chancellor Angela Merkel has said Berlin will not give in to the kidnappers' demands.
